IPSEC fragmentation

Hello, I understand that even if a a Telco Internet circuit supports a standard MTU of 1500 and fragmentation is either not supported or reliable, that this is irrelevant to the fragmentation that may take place on traffic passing via a Fortigate IPSEC tunnel across that Internet circuit i.e. the two concepts are separate.

So, you could have a telco Internet circuit with 1500 MTU and no fragmentation support, but fragmentation can still work WITHIN the Fortigate established IPSEC tunnel.

Am I correct in this thinking ?

Thank you kindly.